ConvertInnerOrCrossJoin.java

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package org.apache.doris.nereids.rules.rewrite;

import org.apache.doris.nereids.rules.Rule;
import org.apache.doris.nereids.rules.RuleType;
import org.apache.doris.nereids.trees.plans.JoinType;

import com.google.common.collect.ImmutableList;

import java.util.List;

/**
 * Convert invalid inner join to cross join.
 * Like: A inner join B on true -> A cross join B on true;
 * Or
 * Convert invalid cross join to inner join.
 * Like: A cross join B on A.id > 1 -> A inner join B on A.id > 1;
 */
public class ConvertInnerOrCrossJoin implements RewriteRuleFactory {
    @Override
    public List<Rule> buildRules() {
        return ImmutableList.of(
            innerLogicalJoin()
                .when(join -> join.getHashJoinConjuncts().isEmpty() && join.getOtherJoinConjuncts().isEmpty()
                        && join.getMarkJoinConjuncts().isEmpty())
                .then(join -> join.withJoinTypeAndContext(JoinType.CROSS_JOIN, join.getJoinReorderContext()))
                .toRule(RuleType.INNER_TO_CROSS_JOIN),
            crossLogicalJoin()
                .when(join -> !join.getHashJoinConjuncts().isEmpty() || !join.getOtherJoinConjuncts().isEmpty()
                        || !join.getMarkJoinConjuncts().isEmpty())
                .then(join -> join.withJoinTypeAndContext(JoinType.INNER_JOIN, join.getJoinReorderContext()))
                .toRule(RuleType.CROSS_TO_INNER_JOIN)
        );
    }
}